The
hash database-map type uses a hashing algorithm
for storing data. This approach to a database is described in
A New Hash Package for UNIX, by Margo Seltzer
(Usenix Proceedings, Winter 1991). The hash type
is available only if sendmail was compiled with
NEWDB defined and the Berkeley or Sleepycat
db(3) library linked.
The hash type is the default that is used with
most of the features offered by the mc
configuration technique (see Table 23-4 in Section 23.5). For example, consider the following:
Kuudomain hash -o /etc/mail/uudomain
Here, a database map named uudomain is declared to
be of type hash. The -o says
that the database file /etc/mail/uudomain is
optional.
Quite a few other database-map switches are available with this type.
The complete list is shown in Table 23-13.
Table 23-13. The hash database-map type K command switches
|
-A
|
-A
|
Append values for duplicate keys
|
|
-a
|
-a
|
Append tag on successful match
|
|
-D
|
-D
|
Don't use this database map if DeliveryMode=defer
|
|
-f
|
-f
|
Don't fold keys to lowercase
|
|
-m
|
-m
|
Suppress replacement on match
|
|
-N
|
-N
|
Append a null byte to all keys
|
|
-O
|
-O
|
Never add a null byte
|
|
-o
|
-o
|
This database map is optional
|
|
-q
|
-q
|
Don't strip quotes from key
|
|
-S
|
-S
|
Space replacement character
|
|
-T
|
-T
|
Suffix to append on temporary failure
|
|
-t
|
-t
|
Ignore temporary errors
|
The -d38.20 command-line switch (-d38.20) can be used to observe this
type's lookups in more detail. See also the
btree type (btree).
